Drill sharpening apparatus



A. H. BOWMAN DRILL SHARPENING APPARATUS Jan. 1,71952 3 Sheets-Sheet lFiled May 25, 1949 Inventor mit.

A/t'uarlv H. Bowman Jan 1, 1952 A. H. BOWMAN 2,580,884

' I DRILL SHARPENING APPARATUS Filed May 25, 1949 s sheets-sheet 2 A"'//////////////,m 66 l! /26 60 54 62 H l Albert H. Bowman Jan. 1, 1952A, H, BOWMAN 2,580,884

DRILL SHARPENING APPARATUS Filed May 25, 1949 3 Sheets-Sheet 5 InventorAlbert H..B0wman v u By WW Patented Jan. 1, 1952 UNITED STATES PATENToFFIcE DRILL SHARPENING APPARATUS Albert H. Bowman, Los Angeles, Calif.Application May 25, 1949, Serial No. 95,210

I I I (C1. 51-21s) 8 Claims.

This invention relates to new and useful improvements and structuralrefinements in drill sharpening apparatus, and the principal object ofthe invention is to provide an apparatus of the character hereindescribed which embodies in its construction a drill holder adapted1 forswinging or rotation on an axis guided by mechanical means so as toassure accurate formation of desired lip angle and lip clearance on thedrill being sharpened,

An important feature of the invention, therefore, resides in thestructural arrangement of the guiding means for the drill holder, andvanother' feature of the invention involves the provision of meanswhereby the apparatus may be adjusted to form lip angles and lipclearances of different angular magnitudes, as well as to form aconstant or a varying lip clearance from the periphery to the axis ofthe drill.

A still further feature of the invention resides in its adjustability toaccommodate drills of various diameters and in its additionaladjustability for the formation of different lip clearances.

An. additional feature of the invention resides in the provision ofgauge means for pre-setting a drill in position in the apparatus, so asto assure that the sharpening operation may be properly7 and correctlyperformed.

VSome of the advantages of the invention reside mits simplicity ofconstruction, in its adaptability for use in association with grindingwheels of different types, and in its adaptability tor economicalmanufacture.

With the above more important objects and features in view and suchother objects and features as may become apparent as this specificationproceeds, the invention consists essentially in the construction andarrangement of parts as shown in the accompanying drawing in which:

Figure 1 is a top plan view of the invention showing a drill in placetherein; l

Figure 2 is a top plan view, similar to that shown in Figure 1, butillustrating the invention in a relatively dierent angular position;

Figure 3 is a side elevational view of the invention as shown in Figurel;

Figure 4 is a perspective View of a supporting member used in theinvention; K

Figure 5 is a perspective view of a carrier used therein;

Figure 6 is a cross-sectional view, taken substantially in the plane ofthe line 6-6 in Figure l Figure 7 is a cross-sectional view, takensubstantially in the plane of the line 1-1 in Figure 6;

Figure 8 is a cross-sectional view, taken substantially in the plane ofthe line 8-8 in Figure 3;-

Figure 9 is a cross-sectional view, taken substantially in the plane ofthe line 9-9 in Figure 3;

Figure 10 is a fragmentary plan View showing the gauge means used ininstalling the invention; and

Figure 1l is a fragmentary front elevational View of the device with thedrill holder in a lowered inoperative position and with the lipaligninggauge contacting the lip of the drill.

Like characters ofA reference are employed to designate like parts inthe specification and throughout the several views.

Referring now-to the accompanying drawings in detail, the inventionconsists of a drill sharpening apparatus designatedgenerally by thereference character 20, the same including a rotatable grinding disk orwhel 22 having a at face 24 with'which the drills are engageable forgrinding or sharpening purposes.

Broadly, the invention resides in the provision of means for holding adrill in a proper predetermined position relative to the face 24 of thegrinding Wheel so that the sharpening operation is eected whilemaintaining proper lip angle of the drill and controlling the lipclearance.

The means referred to in the preceding paragraph consist of a suitablestand 26 which is adapted to be secured by the bolts 23, or the like, toa supporting surface 30, such as for example, the frame of the grinder.`A base member 32, preferably assuming the form of a strap, is formedwith a slot 34 to receive a bolt 36 whereby the member 32 is adjustablysecured to the element 26the base member 32 being also provided with anadditional slot (not shown) to receive a further bolt 33. The bolt 38extends through a slot 4i? provided in a supporting member 42 and asuitable adjusting screw 44 extends through a screw-threaded aperture 46into the slot 4U and is engageable with the bolt 38 for the purpose ofreleasably locking the latter.

The supporting member 42 is substantially horizontal and is providedwith a vertical extension 48, the purpose of which will be hereinafterdescribed. The member 42 is also formed integrally with a tubularportion 50, the bore of which provides a bearing for a pivot pin 52. Thelatteris formed intermediate the ends thereof with a frusto-conicalshoulder 54 which engages a countersink 56 provided in the bore of thebearing 50, the shoulder 54 abutting an arm 58 towhich the pin 52 isrigidly secured by means of a nut 60. Needless to say, the pin 52 isfreely rotatable in the bearing o and is provided with a retaining nut62 locked by a screw and washer 64, `86, respectively (see Fig. 8)whereby the pin 52 is prevented from being withdrawn from the bearing50.

The arm 58 is provided with a lateral extension 68 which, in turn, isformed with a horizontal bore, the axis of the latter being illustratedat 18. The bore of the extension 68 of the arm y58 accommodatesa furtherpivot pin 12 which is similar in construction to the aforementioned pin52 and is rigidly secured to a cam-shaped portion 14 of an L-shapedcarrier 16 by means of a screw 18 extending through an aperture 80 withwhich the cam portion 14 is formed. A nut, washer and lock screwassembly 82' is provided on one end portion of the pivot pin 12' forthe" purpose of rotatably retaining the pivot p in in the extension 6B,the assembly 82 being similar to the aforementioned elements 62, 64, 66.

The axis of the pivot pin 12 is also represented by the aforementionedaxial line 10, and it will be noted that while the cam portion 14 of thecarrier 16 is vertical, the remaining portion of the carrier ishorizontal and is formed with an aperture 84 to receive a screw 88whereby a drill holder assembly 88 is mounted on the carrier'. Theholder assembly 88 includes in its construction a base portion 00 whichis secured to the carrier by the screw 88, whilev a drill cradle S2 isslidable longitudinally on the base portion 90, this being effected byproviding the cradle and the base portion with coacting dovetail guides04. Mechanical means are employed for sliding the cradle 92 on thebaseportion 80, these means consisting of a screw 96 rotatable in ascrew# threaded lug 88 which is formed integrally with the base portion80, the screw 86 rotatably engaging an eye |00 which is screw-threadedasat |02 into the cradle 02 andl is movable in a slot |04 with which thebase portion 90 is provided, as shown in Figure 'l'.

One side of the cradle 492 is formed withA a; V-` shaped channel |06 toreceive a drill |08, this drill being retained in the channel |06 by alaterally shiftable block H0 provided in the cradle S2. This block isactuated by means of a rotatable adjusting screw ||'2 and it will beobserved that the block I0' is also equipped with a guiding pin H13which slidably extends through one side portion of the cradle 92.

A stud ||6 projects outwardly from one end of the cradle 92 and a clamp||8 is slidable on this stud, being adiustably secured in positionthereon by a set screw |20. A shaft |22, disposed in parallelism to stud||6, is slidable through the clamp |i8 and is adjustably and reversiblyse;

cured therein by an additional set screw |24. A

plate or tab |28 is rigidly secured to one end or the shaft |22 and isadapted to abut the drill |88 in the manner shown, so that the positionof the drill in the holder 88 may be preadjusted by setting the clampI8, as will be clearly apparent. Itis to be noted that the position ofthe shaft |22 in the clamp ||8 may be reversed when it is not necessaryto extend the shaft to accommodateextra long drills.

A drill pre-setting gauge |28 is also provided, this gauge simplyassuming the form of an arm which is swingably mounted on a bolt |30,the latter extending through a screw-threaded aperture 232 formed in theaforementioned extension 48 of the 'supporting member 42. The arm |28 isprovided at its outer end with an angu-lated 4 portion |34 which may bealigned with the lips |36 of the drill |08 when the arm |28 is swungtoward the holder 88.

The aforementioned bolt |30 also carries a rotatable cam |38, agraduated indicator disk |40 and a lock nut unit I 42, the latterincluding a nut of the stop nut variety, so that it does not need to betightened against the gauge |28, but permits pivotal movement of thegauge on the bolt |30 independently of the cam |38 and disk |40.Moreover, the indicator disk |48 is conveXo-concave and is formed fromresilient material, so that it frictionally engages the cam |38 anddiscourages rotation of the latter on the bolt |30. A spacer sleeve |44is provided between the disk |40" and the' adjacent surface of theextension 48, so as Yto prevent the disk from collapsing and losing itsresiliency.

It may be explained at this point that the aforementioned holder 88 isadjustable on the carrier 16: inthe direction of the arrow |416, thisbeing effected by simply loosening the screw 86. The relative positionof the holder on the carrier is indicated b'y a pointer |48 formedintegrally with the base` portion 880ithe holder, theA position lof.they pointer |l48` being determined by means of a graduatedN scale |50with which the carrier 16 is provided, asV is' best shown in' Figure5=.-

It willbe' also' observed from the-foregoing that the holder 88 togetherwith the carrier' 18 are swingable about a horizontal axis,- namely, theaxis 10 of the pivot pin.12, this swinging move-l ment being indicatedat |52. in' Figure .A Moreover, it is to' be noted that the holder 88and the carrier 16 are rockable together with theY arm 58 on the pivotpin 52, as indicated at |54 in Figure 3, during which action the camsurface portion 14 of the carrier may engage the cam |38, as shown.However, the arm 58 together with the carrier and drill holder may beswung to a non-operative position illustrated by the phantom lines |56lin Figure 3, in which` position they are supported by anarcuate stopmember or strap |58 which is bolted to the arm 58 as at |60 and isprovided with an angulated end portion |62 which is engageable with theunder sur.- face of the supporting member 42 when the holder is swungtothe inoperative position, as shown.

It will be noted that cam- |38 has an index mark or poi-nter |66, andthe graduated disk |40 has two scales |68 and |10. The scale |68 is usedwhen the axis 10 is set parallel with the face of the grinding wheel asshown in Fig. l, and scale |710 has its graduations spaced further apartthan those of the scale |68y to adapt it for use when the axis 10 is setat an angle to the face of the grinding wheel as shown in Fig. 2. Byloosening bolt |30, the disk Y|l|0may be turned to position the desiredone of said scales at the left of bolt |30, as viewed in Fig. 3, forcoaction with the index mark or pointer |66.

Tov aid in installing the present device upon a grinding machine, agauge |64 is used as shown in Fig. 10. By clamping the gauge |64 inthedrill holder 88, the operator may employ it to align and locate thedevice at a fixed distance relative to the abrasive surface 24,whereupon the bolts 36 and 38 are tightened. Fig. 10 shows the properpositions of the various elements when installing the device'. In orderwords, cams |38 and 14 are engaged, holder 88 is horizontally disposed,and gauge |64 is secured in holder 88 and engaged with the abrasivesurface 24'. At this time, cam index |66 is set at zero on disk |48, andcradle 92 and base 90 are ush at their for-r ward ends, thusestablishing ah iixed distance from the surface 24 to the axis 10.

In use, the diameter of the drill to be sharpened is noted, and theindex |66 on cam |38 is rotated relative to disk |40 to the graduationof the latter designating such diameter. The drill is now inserted inholder 88 While the latter is positioned in the dotted line position |56of Fig. 3, thumb screw I2 is tightened to hold the drill, and shank stop|26 is adjusted to abut the drill shank. The drill is thentemporarilyreleased by loosening screw ||2, whereupon the drill is rotated foralignment under gauge |28, and screw ||2 is again tightened.. The holder88, carrier 16 and arm 58 are then swung upwardly about pivot pin 52 sothat cam 'I4V is engaged with cam |38, whereupon the drill is advancedto the abrasive wheel v22 by the feed .screw 96. The holder 88 is thenoscillated as at |52 about pivot pin 'i2 while maintaining cam i4 inengagement with cam |38 so that proper lip clearance is imparted to thedrill. The magnitude of this lip relief is proportional to the magnitudeof its particular eccentric position and the radius of the oscillatingmotion imparted to the lip.

After the lip |36 of the drill |08 is sharpened in this manner, thescrew ||2 of the holder 88 may be loosened and the drill may be rotatedso that the remaining lip or lips thereof may be sharpened in a likemanner, this being repeated u in instances of multi-lip drills until allthe lips are sharpened to a uniform angle and clearance.

Cam |38, having a convolute form and being pre-set to a graduated scaleon disk |40, acts as a regulator to equalize the radius of theoscillating motion imparted to the drill lip to conform with thevariable eccentric caused by drill core thickness dierences, therebyassuring an approximate sameness of lip clearance on all drills withinthe capacity of the device by proper setting of cam |38 to coincide withthe diameter of the drill. However, the cam |38 may be set at a greateror lesser reading than the drill diameter to form a lip clearance ofdifferent predetermined magnitude without readjustment of screws orbolts.

It is to be observed that when the set-up shown in Figure l is used, theaxis is parallel to the face 24 of the wheel 22, and accordingly, a trueconical grinding action is achieved, which results in the formation of alip clearance of constant magnitude from the periphery to the center ofthe drill. However, if it is desired to gradually increase the lipclearance from the periphery to the center, the bolts 36, 38 may beadjusted so that the axis l0 of the pivot pin l2 is disposed, forexample, at a ten degree angular deviation from the face 24 of the wheel22, as

shown in Figure 2, while the holder 88 is adjusted on the carrier 16 sothat the pointer |48 is in alignment with the 49 degree mark of thescale |50. In this manner, the lip angle of the drill still remains at59, but the angular deviation of the axis l0 from the face 24 of thewheel 22 offsets the conical grinding action from the axis of the drillso that the lip clearance is progressively increased from the peripheryto the center.

Needless to say, while in the foregoing description the lip angle of thedrill was referred to as equalling 59 in accordance with conventionalpractice, the adjustment facilitated by the screws 36, 38, 86 may bevaried so as to accommodate lip angles of other magnitude, as will beclearly apparent.

It is believed that the advantages and use of the invention will beclearly understood from the foregoing' disclosure, and accordingly,further dei scriptionthereof at this point is deemed unnecessary.

Having described the claimed as new is:

f l. In .a drill sharpening apparatus including a grinding wheel, thecombination of a base member extending horizontally and pivotallysecured to af stand, a supporting member which is substantiallyhorizontal and is provided with a longitudinally extending slot in oneend, the opposite end terminating in an integral tubular bore, arockable arm connected to said supporting member and provided with apivot having its axis disposed at a predetermined angle relativeinvention, f .what is to the axis of said grinding wheel, aswingablecarrier mounted on said pivot, a holder mounted on said carrierland adapted to support a drill with a lip of the latter in engagementwith a radial face of the grinding wheel, and means comprising a camengaging surface responsive to the swinging of said carrier for guidingthe rocking movement of said arm so Ias to vary the position of saidholder relative to said grinding wheel and thereby control the lipclearance of the drill being sharpened.

2. The device as defined in claim 1, together with means for adjustingthe angle of the axis of said pivot relative to the axis of saidgrinding wheel, said holder being adjustable relative to the carrier andmeans for adjusting said holder relative to said carrier.

3. The device as dened in claim 1 wherein said means includes a camprovided on said carrier, and a rotatably adjustable cam rest on saidsupporting member engageable by said cam.

4. The device as dened in claim l, wherein said means include a rst camxed on said carrier, and a second rotatable cam adjustably mounted onsaid supporting member and providing a rest for the rst cam, saidcarrier comprising an L-shaped member, and said rst cam being integraltherewith.

5. In a drill support for a drill sharpening machine including agrinding Wheel, the combination of a base member adapted for attachmentto the frame of the machine, a supporting member adjustably mounted onsaid base member, a rockable arm connected to said supporting member andprovided with a pivot having its axis disposed at a predetermined anglerelative to the axis of said grinding wheel; a swingable carrier mountedon said pivot and provided with a cam, a holder comprising a baseportion adjustably mounted on said carrier, a drill cradle slidablelongitudinally on said base portion, and adapted to support a drill witha lip of the latter in engagement with ya radial face of the grindingwheel, means for adjusting the position of said holder on said carrierand a second rotatable cam adjustably mounted on said supporting memberand adapted to be engaged by the first-mentioned cam whereby the rockingmovement of said arm and the swinging movement of said `carrier may beguided to vary the position of said holder relative to said wheel and tocontrol the lip clearance of the drill being sharpened.

6. The device as defined in claim 5, wherein said holder includes a baseportion adjustably attached to said carrier, a drill cradle slidable onsaid base portion toward and away from said wheel, and a pointer andcooperating graduated scale means for indicating the relative positionof the holder on the carrier.

"L The device as defined, in claim 5,. together with a verticallyswingable. drill. presettinggauge mounted. on said supporting member andhaving a horizontal lateral arm engageable with a. lip of a drill insaid. holder when the latter and the carrier are swung away from thegrinding wheel.

8. In a, drill sharpeningk machine, the combination with. a base andintegral arm means thereon, of an' adjustable strap member horizontallydisposed thereon and; pivotally secured to said base, a supportingmember pivoted to said strap member and` extending horizontallyr Saidsupporting member comprising an integral tubular bore. at one end forreceiving a pivot pin, an arm'swingably fastened by said pivot pin, saidarm terminating in a second pivot pin, an L.shaped carrier pivotallysecured to said arm by said second pivot. pin, a drill holder mounted onsaid carrier, said holder having a base portionwhich is secured to saidcarrier, a drill cradle slidably secured on said base portion, a camsurface integral 'with said L-shaped carrier member, a second cam membersecured to said supporting member and cooperating with said rst.mentioned caml surface, and means ccmprising a graduated scale and, diskfor setting the. second cam` member relative to the first cam surface tocontrol the lip clearance of the drill being sharpened.

ALBERT H. BOWMAN.

REFERENCES CITED The following references are of record inl the file ofthis patent:

UNITED STATES PATENTS Number. Name Date 183,798 Champlin Oct. 31., 1876411,845 Walker Oct. 1,. 1889 523,897 Kenyon July 31, 1894 613,127 EamesOct. 25, 1898 707,549 Chandlerl Aug.. 26, 1902 864,546 Lange Aug. 27,1907 1,524,672 Rabut Feb. 3, 1925 1,994,975 Williams Mar. 19, 19352,142,923 Stocking Jan. 3, 1939 2,356,175 Olsonv etal. Aug. 22, 1944

